These are not things that can be taught in a few sentences or a single post. There is no single approach or special secret that allows you to buy a name and make money from it. Selling domain names is a skill, and learning it, just like any other skill (joiner, stock trader, accountant, etc) takes months of studying, and trial and error, then more studying.
Let me give you some sound advice:
While many newcomers don't want to believe this, there really is no get rich quick in domaining. Sure you
can make money in domaining, even get rich, but you need knowledge and experience, and acquiring those traits is not "quick"
Learn properly and you can make money, over time with patience and ready to make mistakes and learn from them, and others.
Here's some good reading for newcomers:
https://www.zandibot.com/10-mistakes-new-domainers-should-avoid-making
https://www.zandibot.com/how-to-pick-two-word-domains
https://www.zandibot.com/three-steps-to-domain-investing-victory-in-2016
Good luck